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Until recently, these models were respectively known as the JX35 and G37, but the company is undergoing a global reorganisation after two decades of being US-focused, prompting a new Q-centric naming convention.

The US, Japan and increasingly, China, figure significantly in Infiniti's calculations – it recently relocated its headquarters to Hong Kong – and these markets tend to prefer gasoline to diesel power. Surely some customers wish to see both hybrid and diesel powertrains from the brand, but Infiniti cannot immediately afford that strategy, said brand president Johan de Nysschen.

“We have to avoid the trap of offering one customer two cars," he said.

Befiting a sport-luxury brand, Infiniti's hybrids are tuned to deliver spirited performance rather than the soft, unemotional driving experience of mainstream hybrids, de Nysschen added.

The QX60 Hybrid uses a new supercharged 2.5-litre gasoline four-cylinder engine in combination with a 15kW electric motor for a total system output of 250 horsepower, while the Q50 uses the same 2.5-litre unit in conjunction with a 50kW motor, yielding total output of 354hp. Grunt is routed through a continuously variable transmission in the QX, while the Q gets a seven-speed automatic that can be controlled with magnesium shift paddles.

The gas engine features an Eaton roots-type supercharger of the company's design, which makes the power booster nearly as efficient as an exhaust-driven turbocharger while preserving the instant torque response characteristic of superchargers.

Both cars reach dealers this summer. The QX60 Hybrid commands a $3,000 premium over the regular QX – which starts at $42,000 – while delivering EPA-estimated combined fuel economy of 26mpg.The base Q50 starts at $37,355, while a Premium-trimmed model lists for $40,205. In comparison, the Hybrid Premium starts at $44,605.